A northern Indiana high school student is in custody after authorities uncovered a plot to commit what they describe as "Columbine-like mass murders."

A student from Penn High School in Mishawaka was being held Thursday at the St. Joseph County Juvenile Justice Center. Prosecutor Michael Dvorak says his office is processing charges for conspiracy to commit murder after police found more than 100 knives and several illegal and dangerous snakes during a search at the teen's home.

The plot was discovered while authorities investigated a threat found written in a school restroom in January that they say is not related.